基于DEM的滑坡碎屑流运动堆积特性研究

Study of the accumulation characteristics of landslide debris flow movement based on DEM

滑坡碎屑流灾害往往具有瞬时性和极强的破坏性,传统监测方法很难对滑坡碎屑流的运动过程进行观察和研究,故根据滑坡碎屑流的堆积形态研究滑坡碎屑流灾害演变规律,为滑坡碎屑流的灾害防护提供理论支持。通过运用离散元的方法,定量地研究场地偏转α和分形维数D对滑坡碎屑流运动堆积特性及滑坡碎屑流堆积体颗粒反序结构特征的影响规律。研究结果表明:滑坡碎屑流颗粒的堆积宽度、冲程和堆积面积随着分形维数的增大而减少,分形维数对堆积体的堆积形态影响较小,颗粒反序结构特征的显著性随着分形维数的增大而减弱;滑坡碎屑流颗粒的堆积宽度、冲程和堆积面积随着偏转角增大而增大,并且冲程与场地偏转角关系模型为二次抛物线模型,堆积体最大厚度随着场地偏转角度的增大而逐渐减小,颗粒反序结构特征的显著性随分形维数的增大而减弱;根据滑坡碎屑流颗粒间的接触特性验证了颗粒间的剪切作用是影响颗粒反序结构的主要因素。

Landslide debris flow hazards are transient and highly destructive,and it is difficult to observe and study the movement process of landslide debris flow by traditional monitoring methods.Therefore,it is necessary to study the evolution of landslide debris flow hazards based on the accumulation pattern of landslide debris flow to provide theoretical support for the disaster protection of landslide debris flow.In this article,the influence of site deflectionαand fractal dimension D on the accumulation characteristics of landslide debris flow and the inverse order structure of landslide debris flow accumulation is quantitatively studied by using the discrete element method.The results show that the accumulation width,stroke and accumulation area of landslide debris flow particles decrease with the increasing of fractal dimension,the influence of fractal dimension on the accumulation morphology of the accumulation body is relatively smaller,and the significance of particle inverse order structure characteristics decreases with the increasing of fractal dimension.The accumulation width,stroke and accumulation area of landslide debris flow particles increase with the increasing of deflection angle,and the relationship between stroke and site deflection angle is modelled as the maximum thickness of the accumulation body gradually decreases with the increasing of site deflection angle,and the significance of the particle anticlockwise structure decreases with the increasing of fractal dimension.According to the contact characteristics of the landslide debris flow particles,it is verified that the inter-particle shear is the main factor affecting the particle anticlockwise structure.